Door bell timer using 555 IC?

[Keithstv]

If you are going to use the 12VAC supply to power the 555 via a bridge and smoothing cap I'd add a 330ohm resistor from the smoothing cap to the +ve supply of the 555 and add a 12V zener across the 555 +ve and -ve supplies with a parallel 47 to 100uF cap. The relay should be run from the output of the smoothing cap.

The zener should prevent the 555 supply from rising to too high a level. I'll amend your circuit later and post it. Or if you're in no great hurry I'll see you on Sunday.

Keith